Nanostructured forms and layers and method for producing them using stable water-soluble precursors

ABSTRACT

A process for preparing a composition for producing nanostructured mouldings and layers comprises contacting an aqueous and/or alcoholic sol of a compound of an element selected from silicon sand metals of the main groups and transition groups of the Periodic Table with species possessing hydrolysable alkoxy groups and comprising at least one organically modified alkoxysilane or a precondensate derived therefrom, under conditions which lead to (further) hydrolysis of the species, and subsequent removal of the alcohol formed and any alcohol already present originally. The process is characterized in that the alcohol is removed in an amount such that the residual alcohol content of the composition is not more than 20% by weight.

This application is a 371 of International Application No.PCT/EP99/02396, filed Apr. 8, 1999.

The present invention relates to nanostructured mouldings and layers andto their preparation via stable water-soluble precursors, and inparticular to nanostructured mouldings and layers suitable for opticalpurposes.

In the literature, processes for preparing transparent materialscomprising organic/inorganic composites, using water-containingprecursors, have already been described for coating purposes.

In particular, JP-A-53-6339 describes the synthesis of a compositestarting from a reactively organically modified silane and an inertlyorganically modified silane and conducting hydrolysis in the presence ofaqueous silica sol and phoshoric acid as hydrolysis catalyst. Thealcohol formed in the condensation reaction is not removed.

JP-A-63-37168 describes the synthesis of a composite from free-radicallycrosslinking, acrylate-based monomers dispersed in an aqueous medium andfrom organically modified silanes, the organic radical of these silaneslikewise constituting, a free-radically crosslinking system, in thepresence of colloidal silica and nonionic surfactants. Hydrolysis andcondensation reactions are conducted in a separate process step. Hereagain, the alcohol formed in the condensation reaction is not removed.

A similar description is contained in JP-A-63-37167 for a system whereinthe silane component possesses cationically crosslinking radicals.

U.S. Pat. No. 5,411,787 describes the synthesis of a composite frompolymeric binders dispersed in water, at least one aminosilane componentand colloidal particles having a size of less than 20 nm. In this casetoo, the alcohol formed by the hydrolysis of the silane is not removed.

U.S. Pat No. 4,799,963 describes the preparation of silane-basedcomposites into which, additionally, colloidal silica or nanoscalecerium oxide is incorporated.

The cited literature references contain no indications concerning themechanism of action and, moreover, little information on the pot life ofthe systems they describe. Likewise, in the majority of cases, there isa lack of information on residual solvent contents, although amathematical reworking of the syntheses suggests residual solventcontents of more than 10% by volume.

On the basis of the prior art as described, an investigation was carriedout into the extent to which a reduction in the water sensitivity, i.e.,in the progress of the hydrolysis and condensation reaction, isachievable through controlled coating of colloidal systems withfunctional silanes, and into the extent to which such systems may beused to prepare stable systems for the production of mouldings andlayers, which are suitable, inter alia, for industrial application.

The object of the present invention, therefore, was to provide a processfor preparing nanostructured mouldings and layers, preferably thosesuitable for optical purposes, via stable water-soluble intermediates.

In accordance with the invention it has been found that aqueous,electrostatically stabilized (and hence extremelyconcentration-sensitive) colloidal suspensions with reactive monomericor oligomeric components (silanes or precondensates thereof) may beapplied by coating and as a-consequence do not display, the course ofconcentration, the effect described by Stern (Z. Elektrochem., 508(1924)) of the aggregation of two particles of like charge as theyapproach one another, and in particular do not display the chemicalreactions, which otherwise proceed spontaneously, between reactivesurface groups of the two particles. The concentration and shifting ofthe reaction equilibrium towards the product side, with formation of thesurface condensates, is achieved by means of the removal, performedunder reduced pressure, of the alcohol formed in the condensationreaction (generally methanol or ethanol), resulting in a combination ofvery high storage stability of the condensates (>14 days) withrelatively low residual solvent contents (generally not more than 20% byweight and in particular not more than 10% by weight).

By virtue of the reversibility of the surface modifier/particle bonding(e.g. hydrogen bonding or metal-oxygen bonding (—Al—O—Si—, —Ti—O—Si—,etc., see e.g. Chem. Mat. 7 (1995), 1050-52)) the process describedabove may be reversed when heat is supplied, so that the particles areable to crosslink, accompanied by solidification. Further reaction mayalso take place by way of appropriately selected organic groups on thesurface modifier (e.g. reaction of these groups with one another).

In this way it is possible to react, for example,. aqueous sols, such asboehmite, TiO₂, ZrO₂ or SiO₂ sols, but also other aqueous sols ofcompounds of metals of the main groups and transition groups of thePeriodic Table, with organically modified alkoxysilanes in such a waythat stripping of the solvent and, if desired, subsequent dispersal ofthe liquid residue in water produces clear solutions which are stableover a relatively long period of time. This stripping of the solvent(alcohol) is necessary in order to take the reaction of the coating ofthe particles with the organically modified alkoxysilanes to a pointwhere a hydrolysis- and condensation-stable liquid system is produced.Using customary techniques, these systems may be employed, for example,for coating purposes and, depending on the functional group on theorganically modified alkoxysilane, may be cured thermally orphotochemically with the aid, if desired, of appropriate catalysts. Inthe case of thermal curing, inorganic networks are formed, and ifappropriate organic groups are used organic linkages are formed inparallel thereto as well. The resultant nanocomposites are notable forhigh transparency. If used as a layer, they exhibit good adhesion to avery large number of substrates, and extremely high scratch resistance.

The present invention accordingly provides a process for preparing acomposition for producing nanostructured mouldings and layers whichcomprises contacting an aqueous and/or alcoholic sol of a compound of anelement selected from silicon and metals of the main groups and thetransition groups of the Periodic Table with species possessinghydrolysable alkoxy groups and comprising at least one organicallymodified alkoxysilane or a precondensate derived therefrom, underconditions which lead to (further) hydrolysis of the species, andsubsequent removal of the alcohol formed and any alcohol already presentoriginally, and is characterized in that the alcohol is removed in anamount such that the residual alcohol content of the composition is notmore than 20% by weight, preferably not more than 15% by weight and, inparticular, not more than 10% by weight.

The present invention also provides the compositions obtainable by theabove process and for their use for producing nanostructured mouldingsand substrates provided with nanostructured layers.

The process of the invention differs from similar processes of the priorart in particular by virtue of the fact that a considerable fraction ofthe solvent (alcohol) present in the system is removed from the system.This shifts the hydrolysis and condensation equilibrium towards theproduct side and brings about stabilization of the corresponding liquidsystem. In general, at least 30% by weight, in particular at least 50%by weight and preferably at least 70% by weight of the theoreticalamount of alcohol formed by hydrolysis of alkoxy groups is removed. Withparticular preference, at least 80% by weight, and more preferably still90% by weight, of this alcohol is removed. This calculation does notinclude any alcohol present originally (e.g. from the sol startingmaterial; it is assumed that the corresponding amount of alcohol isremoved 100%), but does include the amount of alcohol already formedduring the preparation of any precondensates used. As a result, it isgenerally ensured that 10-80% (preferably 20-50%) of all presentcondensable (hydrolysed) groups of the silane undergo a condensationreaction.

The alcohol is removed from the reaction system preferably under reducedpressure, in order to permit excessive thermal loading of the system tobe avoided. In general, when removing the alcohol from the system, atemperature of 60° C., in particular 50° C. and with particularpreference 40° C., should not be exceeded.

In the text below, the starting materials used in the process of theinvention are described in more detail.

The sol which is used may be an aqueous sol, an alcoholic sol or anaqueous/alcoholic sol. Preference is given to using simple aqueous sols.If a sol containing alcohol is used, the alcohol in question preferablyhas 1 to 4 carbon atoms, i.e. is methanol, ethanol, propanol,isopropanol or one of the butanols.

The sol of the invention, comprises one or more compounds (preferablyone compound) of one or more elements selected from silicon and themain-group and transition-group metals. The main-group andtransition-group metals preferably comprise those from the third andfourth main groups (especially Al, Ga, Ge and Sn) and the third to fifthtransition groups (especially Ti, Zr, Hf, V, Nb and Ta) of the PeriodicTable. Alternatively, other metal compounds may lead to advantageousresults, such as those of Zn, Mo and W, for example.

The corresponding element compounds preferably comprise oxides, oxidehydrates, sulphides, selenides or phosphates, particular preferencebeing given to oxides and oxide hydrates. Accordingly, the compoundspresent in the sol used in accordance with the invention comprise inparticular (and preferably) SiO₂, Al₂O₃, AlOOH (especially boehmite),TiO₂, ZrO₂ and mixtures thereof.

The Sol used in the process of the invention generally has a solidscontent of from 5 to 50% by weight, preferably from 10 to 40 and withparticular preference from 15 to 30% by weight.

The species containing hydrolysable alkoxy groups for use in the processof the invention include at least one organically modified alkoxysilaneand/or a precondensate derived therefrom. Organically modifiedalkoxysilanes which are preferred in accordance with the invention arethose of the general formula (I):

R′_(4−x)Si(OR)_(x)  (I)

in which the radicals R are identical or different from one another(preferably identical) and are unsubstituted or substituted (preferablyunsubstituted) hydrocarbon groups having 1 to 8, preferably 1 to 6 andwith particular preference 1 to 4, carbon atoms (especially methyl orethyl), the radicals R′, which are identical or different from oneanother, are each an unsubstituted or substituted hydrocarbon grouphaving 1 to 20 carbon atoms and x is 1, 2 or 3.

Examples of radicals R′ in the above formula are alkyl, alkenyl, aryl,alkylaryl, arylalkyl, arylalkenyl and alkenylaryl radicals (preferablyhaving in each case 1 to 12 and in particular 1 to 8 carbon atoms andincluding cyclic forms) which may be interrupted by oxygen, sulphur,nitrogen atoms or the group NR″ (R″=hydrogen or C₋ alkyl) and may carryone or more substituents from the group of the halogens and of theunsubstituted or substituted amino, amide, carboxyl, mercapto,isocyanato, hydroxyl, alkoxy, alkoxycarbonyl, acryloyloxy,methacryloyloxy or epoxy groups.

Among the above alkoxysilanes of the general formula (I), there is withparticular preference at least one in which at least one radical R′possesses a group which is able to undergo an addition-polymerization(including polyaddition) or condensation-polymerization reaction.

This group capable of addition-polymerization orcondensation-polymerization reaction preferably comprises an epoxy groupor (preferably activated) carbon-carbon multiple bonds (especiallydouble bonds), a (meth)acrylate group being a particularly preferredexample of the last-mentioned groups.

Accordingly, particularly preferred organically modified alkoxysilanesof the general formula (I) for use in the present invention are those inwhich x is 2 or 3, and in particular 3, and one radical (the onlyradical) R′ is ω-glycidyloxy-C₂₋₆ alkyl or ω(meth)acryloyloxy-C₂₋₆alkyl.

Specific examples of such silanes are3-glycidyloxypropyltri(m)ethoxysilane, 3,4-epoxybutyltrimethoxysilaneand 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and also3-(meth)acryloyloxypropyltri(m)ethoxysilane and2-(meth)acryloyloxyethyltri(m)ethoxysilane. Further examples of suitablecompounds in which x is 1 or 2 are3-glycidyloxypropyldimethyl(m)ethoxysilane,3-glycidyloxypropylmethyldi(m)ethoxysilane,3-(meth)acryloyloxypropylmethyldi(m)ethoxysilane and2-(meth)acryloyloxyethylmethyldi(m)ethoxysilane.

Examples of further alkoxysilanes which may be used as they are ifdesired but preferably in combination with alkoxysilanes containing theabove groups capable of addition-polymerization orcondensation-polymerization reaction are tetramethoxysilane,tetraethoxysilane, tetra-n-propoxysilane, tetra-n-butoxysilane,cyclohexyltrimethoxysilane, cyclopentyltrimethoxysilane,ethyltrimethoxysilane, phenylethyltrimethoxysilane,phenyltrimethoxysilane, n-propyltrimethoxysilane,cyclohexylmethyldimethoxysilane, dimethyldimethoxysilane,diisopropyldimethoxysilane, phenylmethyldimethoxysilane,phenylethyltriethoxysilane, phenyltriethoxysilane,phenylmethyldiethoxysilane and phenyldimethylethoxysilane.

Especially if the nanostructured mouldings and layers of the inventionare to be given dirt and water repellency properties and a low surfaceenergy, it is possible together with the organically modifiedalkoxysilane to use silanes possessing directly, silicon-attachedfluorinated alkyl radicals having at least 4 carbon atoms (andpreferably at least 3 fluorine atoms), with the carbon atoms positionedα and β to the silicon preferably carrying no fluorine atoms, examplesbeing (tridecafluoro-1,1,2,2-tetrahydrooctyl)methyldiethoxysilane,(tridecafluoro-1,1,2,2-tetrahydrooctyl)triethoxysilane,(heptadeca-fluoro-1,1,2,2-tetrahydrodecyl)methyldiethoxysilane and(heptadecafluoro-1,1,2,2-tetrahydrodecyl)triethoxysilane.

Of course, in addition to the above silanes (especially the organicallymodified silanes), the species with hydrolysable alkoxy groups that areused in accordance with the invention may further comprise species otherthan silanes. Examples of such non-silane species are alkoxides(preferably with C₁₋₄ alkoxy groups) of aluminium, titanium zirconium,tantalum, niobium, tin, zinc, tungsten, germanium and boron. Specificexamples of such compounds are aluminium sec-butylate, titaniumisopropoxide, titanium propoxide, titanium butoxide, zirconiumisopropoxide, zirconium propoxide, zirconium butoxide, zirconiumethoxide, tantalum ethoxide, tantalum butoxide, niobium ethoxide,niobium butoxide, tin t-butoxide, tungsten(VI) ethoxide, germaniumethoxide, germanium isopropoxide and di-t-butoxyaluminotriethoxysilane.

Especially in the case of the relatively reactive alkoxides (e.g. thoseof Al, Ti, Zr etc.), it may be advisable to use them in complexed form,examples of suitable complexing agents being, for example, unsaturatedcarboxylic acids and β-dicarbonyl compounds, such as methacrylic acid,acetylacetone and ethyl acetoacetate, for example. If species containinghydrolysable alkoxy groups, other than the organically modifiedalkoxysilanes, are used, then the molar ratio of the organicallymodified alkoxysilanes to the other species is preferably at least 2:1,in particular at least 5:1 and with particular preference at least 10:1.

If use is made in the process of the invention, as is preferred, oforganically modified alkoxysilanes containing a group capable ofaddition-polymerization or condensation-polymerization reaction, then itis preferred to incorporate into the corresponding composition, inaddition, a starter component, the molar ratio of starter to organicgroup generally not exceeding 0.15:1.

Where, for example, silanes of the general formula (I) containing epoxygroups are used, suitable starters include, in particular, imidazoles,amines, acid anhydrides and Lewis acids. If imidazoles are to be used,1-methylimidazole is particularly preferred. Other preferred examples ofimidazole starters are 2-methylimidazole and 2-phenylimidazole. Examplesof the starters from the group of the primary, secondary and tertiaryamines are ethylenediamine, diethylenetriamine, triethylenetetramine,1,6-diamino-hexane, 1,6-bis(dimethylamino)hexane,tetramethyl-ethylenediamine, N,N,N′,N″,N″-pentamethyldiethylenetiramine,1,4-diazabicyclo[2.2.2]octane, cyclohexane-1,2-diamine,2-(aminomethyl)-3,3,5-trimethylcyclopentylamine,4,4′-diaminocyclohexylmethane, 1,3-bis(aminomethyl)cyclohexane,bis(4-amino-3-methylcyclohexyl)methane, 1,8-diamino-p-menthane,3-(aminoethyl)-3,3,5-trimethylcyclohexylamine (isophoronediamine),piperazine, piperidine, urotropine, bis(4-aminophenyl)methane andbis(4-aminophenyl) sulphone. The amines used as starters may also befunctionalized with silanes. Examples areN-(2-aminoethyl)-3-aminopropyltriethoxysilane,N-(2aminoethyl)-3-aminopropyltrimethoxysilane,aminopropyltrimethoxysilane and aminopropyltriethoxysilane. In addition,boron trifluoride adducts of amines, such as BF₃-ethylamine, forexample, may be used. Furthermore, organic crosslinking may be broughtabout with the aid of acid anhydrides (preferably in combination withtertiary amines), such as ethylbicyclo[2.2.1]heptene-2,3-dicarboxylicanhydride, hexahydronaphthalenedicarboxylic anhydride, phthalicanhydride, 1,2-cyclohexanedicarboxylic anhydride, and also[3-(triethoxysilyl)propyl]succinic anhydride.

Catalysts additionally suitable for the crosslinking of epoxy groups inthe present case are (optionally prehydrolysed) alkoxides of aluminium,titanium and zirconium, e.g. Al(OC₂H₄OC₄H₉)₃, and organic carboxylicacids, such as propionic acid, for example.

In the case of the use of silanes of the above formula (I) which possess(meth)acrylate groups, a conventional thermal polymerization catalyst ora conventional photopolymerization catalyst may be added to thecomposition. Examples of thermal catalysts used with preference areazobisisobutyronitrile, diacyl peroxides (e.g. dibenzoyl peroxide anddilauroyl peroxide), peroxydicarbonates, alkyl peresters, perketals,alkyl or aryl peroxides, ketone peroxides and hydroperoxides.

It is of course also possible to incorporate into the composition purelyorganic components which react with reactive groups on the silanes ofthe general formula (I) and so are able to bring about furthercrosslinking in the course of curing. For example, in the case of theuse of silanes containing (meth)acrylate group, specific examples ofuseful crosslinking agents are bisphenol A bisacrylate, bisphenol Abismethacrylate, trimethylolpropane triacrylate, trimethylolpropanetrimethacrylate, neopentyl glycol dimethacrylate, neopentyl glycoldiacrylate, diethylene glycol diacrylate, diethylene glycoldimethacrylate, triethylene glycol diacrylate, triethylene glycoldimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycoldimethacrylate, polyethylene glycol diacrylate, polyethylene glycoldimethacrylate, 2,2,3,3-tetrafluoro-1,4-butanediol diacrylate anddimethacrylate, 1,1,5,5-tetrahydroperfluoropentyl-1,5-diacrylate anddimethacrylate, hexafluorobisphenol A diacrylate and dimethacrylate,octafluoro-1,6-hexanediol diacrylate and dimethacrylate,1,3-bis(3-methacryloyloxypropyl)tetrakis(trimethylsiloxy) disiloxane,1,3-bis(3-acryloyloxypropyl)tetrakis(trimethylsiloxy)disiloxane,1,3-bis(3-methacryloyloxypropyl)tetramethyldisiloxane and 1,3-bis(3-acryloyloxypropyl)tetramethyldisiloxane.

If nanostructured mouldings and layers having hydrophilic properties aredesired, it is possible, for example, to incorporate into thecomposition of the invention, additionally, components which lead tosuch hydrophilic properties For this purpose it is possible to usecomponents covalently bondable to the inorganic matrix (e.g. a componentwith a free hydroxyl group, such as 2-hydroxyethyl (meth)acrylate or ahydrophilic component which is freely movable in the matrix (e.g. asurfactant) or a combination of the two.

The conditions to be used in accordance with the invention, leading to(further) hydrolysis of the species containing hydrolysable alkoxygroups and/or the corresponding precondensates, preferably comprise thepresence of at least 0.5 mol of H₂O per hydrolysable alkoxy group. Thisamount of water is generally already present by virtue of the water inthe sol. If this is not the case, the corresponding amount of watershould be added separately.

It is more preferable if a catalyst for the hydrolysis (andcondensation) of the alkoxy groups is present. Preferred catalysts forthis purpose are acidic catalyts, e.g. aqueous (mineral) acids such asHCl, for example.

The proportion of the starting materials used (sol and speciescontaining hydrolysable alkoxy groups) is preferably chosen such that inthe final moulding or in the final layer (after curing) the solidscontent originating from the sol makes up from 1 to 50% by weight and inparticular from 5 to 30% by weight of the moulding or layer,respectively.

The method of contacting the aqueous and/or alcoholic sol with thespecies containing hydrolysable alkoxy groups under conditions whichlead to hydrolysis of the species containing alkoxy groups is familiarto the skilled worker and is elucidated further in the examples below.Following the removal of the solvent (alcohol) from the composition(which generally means that from 10 to 80% and in particular from 20 to50% of the initial hydrolysable alkoxy groups have undergone acondensation reaction), it may prove to be advantageous for certainpurposes to adjust the resultant composition to an appropriate viscosityby adding water. Preferably, the viscosity of the composition,especially for coating purposes, is below 5000 mPas, in particular below3000 mPas.

To produce nanostructured mouldings and substrates provided withnanostructured layers, with the aid of the composition of the invention,this composition is either introduced into a mould or applied to asubstrate and subsequently—if desired after drying beforehand at roomtemperature or at slightly elevated temperature, especially in the caseof the production of layers—thermal (and additionally, if desired,photochemical) curing is conducted. In the case of the production oflayers, all conventional coating techniques may be used, e.g. dipping,flowcoating, rolling, spraying, knife coating, spincoating or screenprinting.

The curing temperature is generally, in the range from 90° C. to 300°C., in particular from 110° C. to 200° C., and in the case of layerproduction is also dependent, in particular, on the temperaturestability of the substrate to be coated.

As already mentioned at the outset, the composition of the invention issuitable for coating a very wide variety of substrates and on thosesubstrates, even without surface treatment, in many cases displays verygood adhesion and extremely high scratch resistance. Particularlypreferred substrates for layer production are glass, transparent andnon-transparent plastics, and metals. Examples of suitable plastics arepolycarbonate, poly(meth)acrylates, polystyrene, polyvinyl chloride,polyethylene terephthalate, polypropylene and polyethylene, while apreferred metal substrate is aluminium.

Accordingly, the compositions obtainable in accordance with theinvention are suitable for a large number of applications. Examples ofsuch applications are, in particular, the following:

Coating to increase scratch and abrasion resistance:

topcoats of household articles and means of transport

transparent and non-transparent polymer components

metallic substrates

ceramic and glass substrates

Coating to improve the abrasion and corrosion resistance of precious andnon-precious metals:

Mg: engine blocks, spectacle frames, sports equipment, wheel rims,transmission casings

Al: bodywork of means of transport, wheel rims, facing elements,furniture, heat exchangers

Steel: compression moulds for producing components, sanitary fittings

Zn: roof constructions, firearms, airbag accelerometer masses

Cu: door fittings, heat exchangers, washbasins

Coatings for improving cleaning behaviour: Concerning examples for thisapplication, reference may be made to DE-A-19544763.

Coatings for improving the demoulding of components and for reducingadhesion:

Metal and polymer conveyor belts

Rolls for polymerization reactions

Compression moulds for producing polystyrene components

Anti-graffiti coatings on topcoats and facings

Coatings for anti-condensation effect:

Glasswork of means of transport

Spectacle lenses

Mirrors (e.g. bathroom, automotive rearview and cosmetic mirrors)

Optical components (e.g. spectroscopy mirrors and laser prisms)

Elements for encapsulation (e.g. housings for meteorologicalinstruments)

Coatings for anti-reflection properties:

Polymer or glass covers of display elements (e.g. automotive dashboards,display window glazing)

Coatings for food-related applications:

Diffusion barrier layers (preventing the diffusion of, for example,gases, acetaldehyde, lead ions or alkali metal ions, odorants andflavours)

Coating of hollow glass articles:

Coatings of beverage bottles for increasing the bursting pressure

Colouring of colourless glass by means of a coating

Production of optical mouldings and self-supporting films:

Nanocomposite spectacle lenses

Scratch- and abrasion-resistant packaging films

The examples which follow serve to elucidate further the presentinvention. In all of these examples, the solvent formed by thehydrolysis (ethanol) was removed to an extent of at least approximately95%.

EXAMPLE 1

27.8 g (0.1 mol) of (3-glycidyloxypropyl)triethoxysilane (GLYEO) wereadmixed with 27.8 g of silica sol (30% strength by weight aqueoussolution of SiO₂, Levasile® 200S from Bayer). The mixture wassubsequently stirred at room temperature for 5 hours. Thereafter, theethanol formed by hydrolysis was removed by distillation (rotaryevaporator, maximum bath temperature 40° C.). The residue was admixedwith 1.11 g (0.0005 mol) ofN-(2-aminoethyl)-3-aminopropyltrimethoxysilane (DIAMO) and stirred atroom temperature for one hour.

The resultant system was used to coat polycarbonate and aluminium sheetsand also CR-39 lenses. The polycarbonate sheets had been pretreated bycorona discharge. The coated polycarbonate and aluminium sheets werestored at room temperature for 30 minutes and then cured at 130° C. for4 hours. The CR-39 lenses were stored at room temperature for 30 minutesand then cured at 90° C. for 4 hours.

EXAMPLE 2

Example 1 was repeated but using 3.05 g (0.001 mol) of[3-(triethoxysilyl)propyl]succinic anhydride (GF20) instead of DIAMO.Investigation of the abrasion resistance of polycarbonate sheets coatedwith this composition, by the Taber abrasion test (wheel material CS10F, 1000 cycles, wheel load 500 g), gave a diffuse-light loss of 7%.

EXAMPLE 3

Example 1 was repeated but using a boehmite suspension (2.78 g ofDisperal® P3 in 25 g of distilled water) instead of the silica sol.

EXAMPLE 4

Example 3 was repeated but using 3.78 g (0.01 mol) of Al(OEtOBu)₃ as thecatalyst instead of DIAMO.

EXAMPLE 5

27.8 g (0.1 mol) of GLYEO were admixed with 27.8 g of the silica soldescribed in Example 1. The mixture was subsequently stirred at roomtemperature for 5 hours, followed by removal of the ethanol formed byhydrolysis, as described in Example 1. The residue was admixed with 2.84g (0.01 mol) of TiO₂ sol, prepared as described below, and stirred atroom temperature for one hour.

The TiO₂ sol was prepared by dissolving 28.42 g (0.1 mol) oftetraisopropyl orthotitanate (Ti(OiPr)₄) in 60 ml of isopropanol andadding concentrated hydrochloric acid to the solution in a molar ratioof 1:1. After 2 hours of stirring at room temperature, the volatileconstituents were removed by a rotary evaporator and the residue wastaken up in 70 ml of water.

EXAMPLE 6

139.0 g (0.5 mol) of GLYEO were mixed with 62.4 g (0.3 mol) oftetraethoxysilane (TEOS). The reaction mixture was admixed with anHCl-acidic boehmite suspension (12.82 g of nanoscale boehmite powder in128.20 g of 0.1 N HCl solution) and stirred at room temperature for 5hours. The ethanol formed by hydrolysis was removed by distillation asdescribed in Example 1. Subsequently, 3.78 g (0.01 mol) of Al(OEtOBu)₃were added to the mixture, followed by 1 hour of stirring at roomtemperature.

Polycarbonate plates pretreated by corona discharge andplasma-pretreated CR-39 lenses were coated with the composition thusprepared and cured thermally at 130 and, respectively, 90° C. for onehour.

EXAMPLE 7

29.0 g (0.1 mol) of 3-methacryloyloxypropyltriethoxysilane were admixedwith 29.0 g of the silica sol described in Example 1 and stirred at roomtemperature for 16 hours. The mixture was subsequently admixed with 13.0g (0.1 mol) of 2-hydroxyethyl methacrylate (as hydrophilic component:)and stirred at room temperature for 30 minutes. This was followed bydistillative removal (as described in Example 1) of the alcohol formedby hydrolysis from the reaction mixture. 0.48 g of dibenzoyl peroxide (1mol% based on double bonds present) was added to the concentratedreaction mixture.

The composition thus prepared was applied to polymethyl methacrylatesheets pretreated by corona discharge, and was cured thermally at 95° C.for 4 hours.

EXAMPLE 8

55.6 g of 3-glycidyloxypropyltriethoxysilane were admixed with 0.51 g oftridecafluoro-1,1,2,2-tetrahydrooctyl-l-triethoxysilane and stirred. Theresultant mixture was admixed with 10.85 g of 0.1 N HCl (correspondingto the stoichiometric amount of water for the hydrolysis of thealkoxysilanes). After stirring at room temperature for 24 hours, 55.6 gof the silica sol described in Example 1 were added and the mixture wasstirred at room temperature for 4 hours. The alcohol formed byhydrolysis was removed as described in Example 1 on a rotary evaporator(amount removed 26.4 g). Subsequently, 2.22 g of DIAMO were added andthe mixture was stirred at room temperature for a further hour.

EXAMPLE 9

278.42 g of GLYEO was cohydrolysed with 10 g of a reaction product of3-isocyanatopropyltriethoxysilane and polyethylene glycol 600, togetherwith 54 g of 0.1 N HCl, with stirring at room temperature for 5 hours.The ethanol formed in the prehydrolysis was stripped off on a rotaryevaporator (bath temperature 25° C., 30-40 mbar). Subsequently, 926 g ofthe silica sol described in Example 1 were, incorporated into thismixture with stirring, after which the mixture was stirred at roomtemperature for 16 hours. Thereafter, 11.12 g of DIAMO were added asstarter and the mixture was stirred at room temperature for a furtherhour. Then 20 g of a silicone-based nonionic surfactant were added withvigorous stirring.

Float glass substrates coated with the resultant composition were curedin a drying oven at 130° C. for 4 hours.

EXAMPLE 10

Example 1 was repeated but using 1.32 g (0.005 mol) oftrimethoxysilylpropyldiethylenetriamine. (TRIAMO) instead of DIAMO.

EXAMPLE 11

Example 1 was repeated but using 0.74 g (0.01 mol) of propionic acid asstarter instead of DIAMO.

EXAMPLE 12

Example 1 was repeated but using 3.87 g (0.01 mol) of Al(OEtOBu)₃ asstarter instead of DIAMO.

EXAMPLE 13

Example 1 was repeated but using 0.41 g (0.005 mol) of 1-methylimidazoleas starter instead of DIAMO.

EXAMPLE 14

Example 1 was repeated but using, instead of DIAMO, 5.27 g (0.01 mol) ofa mixture obtained by purifying 3-aminopropyltriethoxysilane (AMEO) withGF20 in a molar ratio of 1:1 with ice cooling.

EXAMPLE 15

Example 6 was repeated but using 95.5 g of the silica sol described inExample 1 instead of the HCl-acidic boehmite suspension, and increasingfivefold the amount of catalyst.

Polycarbonate sheets pretreated by corona discharge andplasma-pretreated CR-39 lenses were coated with the resultantcomposition and cured thermally at 130° C. and 90° C., respectively, forone hour.

EXAMPLE 16

27.8 g (0.1 mol) of GLYEO were admixed with 13.5 g of 0.1 N HCl andstirred at room temperature for 2 hours. 27.8 g of organosol (30% byweight SiO₂ in isopropanol, Bayer PPL 6454-6456) were added to thisprehydrolysate, and the mixture was stirred at room temperature for 5hours. Subsequently, the ethanol formed by hydrolysis and theisopropanol solvent were removed by distillation. The residue wasadmixed with 18.9 g of H₂O (pH 3.2). Subsequently, 1.11 g (0.0005 mol)of DIAMO were added with vigorous stirring and the mixture was stirredat room temperature for 1 hour.

The resultant composition was used to coat polycarbonate and aluminiumsheets and also CR-39 lenses. The polycarbonate sheets had beenpretreated by corona discharge. The coated polycarbonate and aluminiumsheets were stored at room temperature for 30 minutes and then cured at130° C. for 4 hours. The CR-39 lenses were stored at room temperaturefor 30 minutes and then cured at 90° C. for 4 hours.

EXAMPLE 17

139.0 g (0.5 mol) of GLYEO were mixed with 62.4 g (0.3 mol) of TEOS andadmixed stoichiometrically with 0.1 N hydrochloric acid. The reactionmixture was stirred at room temperature for 16 hours. Subsequently, theethanol formed by hydrolysis and condensation was removed bydistillation. The concentrated reaction mixture was then admixed with anHCl-acidic boehmite suspension (12.82 g of boehmite powder in 128.8 g of0.1 N HCl solution) and stirred at room temperature for 3 hours. 3.78 g(0.01 mol) of Al(OEtOBu)₃ were then added dropwise to the mixture. Thecoating material thus prepared was stirred at room temperature forapproximately 4 hours.

Corona-pretreated polycarbonate sheets and plasma-pretreated CR-39lenses were coated and cured thermally at 130° C. and, respectively, 90°C. for one hour.

EXAMPLE 18

139.0 g (0.5 mol) of GLYEO were mixed with 62.4 g (0.3 mol) of TEOS andadmixed stoichiometrically with 0.1 N hydrochloric acid. The reactionmixture was stirred at room temperature for 16 hours. Subsequently, theethanol formed by hydrolysis and condensation was removed bydistillation. The concentrated reaction mixture was then admixed with a30% by weight acidified silica sol solution (see Example 1) and stirredat room temperature for 3 hours. 18.9 g (0.05 mol) of Al(OEtOBu)₃ werethen added dropwise to the mixture. The coating material thus preparedwas stirred at room temperature for approximately 4 hours.

Corona-pretreated polycarbonate sheets and plasma-pretreated CR-39lenses were coated and cured thermally at 130° C. and, respectively, 90°C. for one hour.

EXAMPLE 19

27.8 g (0.1 mol) of GLYEO were admixed with 0.51 g of fluorosilane (see,Example 8; 1 mol % with respect to GLYEO) and the mixture was stirred.The mixture was admixed with 5.46 g of 0.1 N HCl, corresponding to thestoichiometric amount of water for the hydrolysis. The mixture wassubsequently stirred at room temperature for 24 hours. Subsequently, thealcohol formed by hydrolysis and condensation was removed on a rotaryevaporator. The residue was admixed with 3.87 g (0.01 mol) ofAl(OEtOBu)₃ and 27.8 g of acidified silica sol (see Example 1) andstirred at room temperature for 3 hours.

EXAMPLE 20

27.8 g (0.1 mol) of GLYEO were admixed with 0.255 g of fluorosilane (seeExample 8; 0.5 mol % with respect to GLYEO) and the mixture was stirred.The mixture was admixed with 5.43 g of 0.1 N HCl, corresponding to thestoichiometric amount of water for the hydrolysis. The mixture wasstirred at room temperature for 24 hours and then the alcohol formed byhydrolysis was removed on a rotary evaporator. The amount removed,approximately 13 g, corresponds to approximately 95%. The residue wasdispersed with a boehmite suspension (2.78 g of Dispersal® P3 in 25 mlof 0.1 N hydrochloric acid solution), admixed with 1.89 g (0.005 mol) ofAl(OEtOBu)₃ and stirred at room temperature for one hour.

What is claimed is:
 1. A process for preparing a composition forproducing a nanostructured moulding or layer, comprising the steps of:(a) contacting an aqueous and/or alcoholic sol of at least one compoundof at least one element selected from the group consisting of siliconand the metals of the main groups and transition groups of the PeriodicTable with at least one species possessing at least one hydrolyzablealkoxy group and comprising at least one organically modifiedalkoxysilane or a precondensate derived therefrom, under conditionswhich lead to hydrolysis of the at least one species; and (b)subsequently removing the total amount of any solvent alcohol alreadypresent originally and at least 30% by weight of the solvent alcoholthat would be formed by the hydrolysis of all alkoxy groups originallypresent in the at least one species, in an amount such that the residualsolvent alcohol content of the composition is not more than 20% byweight.
 2. The process of claim 1, further comprising: (c) adding waterto the composition to achieve an appropriate viscosity.
 3. The processof claim 1 where the sol is an aqueous sol.
 4. The process of claim 1where the at least one compound constituting the sol is derived from atleast one element selected from the group consisting of silicon and themetals of the third and fourth main groups and of the third throughfifth transition groups of the Periodic Table.
 5. The process of claim 1where the at least one compound constituting the sol comprises at leastone oxide, oxide hydrate, sulfide, selenide, or phosphate.
 6. Theprocess of claim 1 where the sol comprises a sol of SiO₂, Al₂O₃, AlOOH,TiO₂, ZrO₂, or a mixture thereof.
 7. The process of claim 1 where theconditions which lead to hydrolysis of the at least one speciespossessing at least one hydrolyzable alkoxy group comprise the presenceof at least 0.5 mol of H₂O per hydrolyzable alkoxy group and a catalystfor the hydrolysis reaction.
 8. The process of claim 1 where the amountof the sol is such that the sol solids content comprises from 1 to 50%by weight of the finished moulding or finished layer.
 9. The process ofclaim 1 where the organically modified alkoxysilane comprises at leastone compound of the formula R′_(4−x)Si(OR)_(x) where: each R, which maybe the same or different, is an unsubstituted or substituted hydrocarbongroup having 1 to 8 carbon atoms, each R′, which may be the same ordifferent, is an unsubstituted or substituted hydrocarbon group having 1to 20 carbon atoms, and x is 1, 2 or
 3. 10. The process of claim 9where: each R is a C₁₋₄ alkyl group, the or at least one R′ possesses agroup capable of an addition-polymerization orcondensation-polymerization reaction, and x is 2 or
 3. 11. The processof claim 10 where the group capable of an addition-polymerization orcondensation-polymerization reaction is an epoxy group or acarbon-carbon multiple bond.
 12. The process of claim 10 where the or atleast one R′ is an ω-glycidyloxy-C₂₋₆ alkyl group, an ω-acryloyloxy-C₂₋₆alkyl group, or an ω-methacryloyloxy-C₂₋₆ alkyl group.
 13. The processof claim 10 further comprising adding to the composition a catalyst forthe addition-polymerization or condensation-polymerization reaction. 14.A composition for producing a nanostructured moulding or layer preparedby the process of claim
 1. 15. A process for producing a nanostructuredmoulding or a substrate provided with a nanostructured layer,comprising: (a) preparing a composition by the process of claim 1; (b)introducing the composition into a mould or applying the composition toa substrate; and (c) thermally and optionally photochemically curing thecomposition to form the moulding or layer.
 16. The process of claim 15where the substrate is a glass, plastic, or-metal substrate.
 17. Ananostructured moulding or a substrate provided with a nanostructuredlayer prepared by the process of claim
 15. 18. An optical componentcomprising the nanostructured moulding or the substrate provided with ananostructured layer of claim 17.